Who are these guys and what the heck are they doing driving alien-looking vehicles in the middle of the Arizona desert? I can tell you two things: One, looking at the cool gallery, I wish I was one of them.
And two, I hope the fridges on their backs are full of cold beer.
These guys are NASA's Desert RATS, a team dedicated to test space vehicles like the Lunar Electric Rover or the Chariot, which will move astronauts across the Moon and Mars' terrains in the Constellation missions. They are now in the Arizona desert demonstrating the feasibility of the vehicles and the future astronauts' Extra-Vehicular Activities.
One of the many things they are testing is what you can see in the photo above: Suit Ports. The suit ports are located on the Lunar Electric Rover's aft. The are designed to let astronauts get in and out their suits very quickly, using a rear-entry hatch. They are equipped with alignment guides and electromagnetic mechanisms to lock and unlock to the hatch, so astronauts only have to get in, unlock, go do their thing, and then just lock to the LER again, and get out of the suit as quickly as they got in. Neat. [NASA]